Nephronophthisis (NPH) is an autosomal recessive kidney disease and the most common genetic cause of end stage renal disease in infants, children and young adults. NHP is caused by a mutation in one of at least six different genes (NPHP1-NPHP6) and other disease loci remain unidentified. NPHP and other cystic kidney diseases such as autosomal dominant polycystic kidney disease (ADPKD) are associated with defects in cilia. While the NPHP protein products (the nephrocystins) are localized to cilia, their cellular and molecular functions in this sensory organelle remain largely unknown. Using Caenorhabditis elegans as a model to study the nephrocystins in a native environment, we will (1) Determine whether the nephrocystins are required for ciliary development or morphology; (2) Explore a role for the nephrocystins in ciliary protein transport. These studies will provide valuable insight into the biogenesis of cilia and human ciliary diseases. [unreadable] [unreadable] [unreadable]